While backporting JDK-8234779 I noticed a handful of additional cases where the NONCOPYABLE macro should probably be applied. For example, in src/hotspot/share/utilities/formatBuffer.hpp.

I think the best way to identify any remaining cases like this is to manually examine every place where a copy constructor is declared. This approach is practical as there only seems to be about 30 copy constructors in mainline at the moment. I believe something like the following search should catch all of them:

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find . -name "*.hpp" |xargs grep -E '\b(\w+)\s*[\(]\s*(const)*\s*(volatile)*\s*\1\s*[&]\s*\w*\s*[\)]'
===

We should look at each result one-by-one and determine if the author was trying to prevent copying. We can replace these cases with the NONCOPYABLE macro where appropriate.